1. Technical Field
The present invention relates to data processing and, in particular, to logically partitioned data processing systems. Still more particularly, the present invention provides a method, apparatus, and program for sharing logical resources among separate partitions in a logically partitioned data processing system.
2. Description of Related Art
Large symmetric multi-processor data processing systems, such as IBM eServer P690, available from International Business Machines Corporation, DHP9000 Superdome Enterprise Server, available from Hewlett-Packard Company, and the Sunfire 15K server, available from Sun Microsystems, Inc. may be partitioned and used as multiple smaller systems. These systems are often referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platform's physical resources. These platform allocable resources include one or more architecturally distinct processors with their interrupt management area, regions of system memory, and input/output (I/O) adapter bus slots. The partition's resources are represented by the platform's firmware to the operating system image.
Each distinct operating system or image of an operating system running within a platform is protected from each other such that software errors on one logical partition cannot affect the correct operation of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for insuring that the various images cannot control any resources that have not been allocated to that image. Furthermore, software errors in the control of an operating system's allocated resources are prevented from affecting the resources of any other image. Thus, each image of the operating system or each different operating system directly controls a distinct set of allocable resources within the platform.
With respect to hardware resources in a logical partitioned data processing system, these resources are disjointly shared among various partitions. These resources may include, for example, input/output (I/O) adapters, memory modules, non-volatile random access memory (NVRAM), and hard disk drives. Each partition within an LPAR data processing system may be booted and shut down over and over without having to power-cycle the entire data processing system.